9.4 Renal

Question 1

Where are the kidneys located?

Answer 1

Retroperitoneal - lie against the dorsal body wall, outside of peritoneum
Flank the vertebral column laterally
Extend from T12 to L3 and receive protection from the floating ribs
Right kidney is slightly lower and more medial than the left

Question 2

What connective tissue surrounds the kidney?

Answer 2

Renal fascia – superficial layer of dense CT, anchors the kidneys to surrounding structures and posterior abdominal wall
Adipose capsule – intermediate layer of fat which cushions and holds the kidneys in place
Renal capsule – transparent layer of fibrous CT adhering directly to the kidney surface

Question 3

What are the renal cortex and medulla? Regions of each?

Answer 3

Renal Cortex – outer region, light granular appearance
Renal Medulla – deep to the cortex
Medullary pyramids – triangular structures which appear striated. Apex is called the renal papilla
Renal columns – extensions of cortex-like tissue separating the medullary pyramids

Question 4

What is the renal pelvis? Regions?

Answer 4

Renal pelvis – flat funnel shaped cavity
Calyces – cup shaped extensions of the renal pelvis
Minor calyx – enclose and collect urine from the renal papilla
Major calyx – minor calyces drain into major which flow to the renal pelvis

Question 5

What are ureters? What kind of epithelium/layers?

Answer 5

Slender tubes extending from the renal pelvis and enter the bladder posteriorly
Lined by transitional epithelium and surrounded by an inner longitudinal and outer circular layer of smooth muscle

Question 6

What is the urinary bladder? Where is it?

Answer 6

collapsible muscular sac that temporarily stores urine
Located in the true pelvis, posterior to the pubic symphysis
Males: anterior to the rectum / superior to the prostate
Females: anterior to the vagina / inferior to the uterus

Question 7

What is the muscle of the bladder? How is it innervated?

Answer 7

Detruser muscle: muscle of the bladder wall (muscularis)
Filling:
sympathetic innervation: relaxes detrusor muscle, tightens internal urethral sphincter
Micturition: (urine exits)
parasympathetic innervation: contracts detrusor muscle, relaxes internal urethral sphincter

Question 8

What is the trigone?

Answer 8

smooth triangular region (no rugae) outlined by the two ureter and single urethra openings

Question 9

What are the sphincters of the urethra?

Where are they?

Answer 9

Release of urine is controlled by two sphincters
Internal urethral sphincter (involuntary) – smooth muscle at the junction of the bladder and urethra
External urethral sphincter (voluntary) – skeletal muscle at the muscular pelvic floor

Question 10

Compare female/male urethras

Answer 10

Female: Length is 3 – 5 cm (relatively short)
Lined by transitional epithelium near the bladder and progressively changes to stratified squamous near the external sphincter

Male: Length is 18 – 20 cm (relatively long)
Epithelium changes from transitional to pseudostratified columnar to stratified squamous
Three regions:
Prostatic urethra – from base of bladder through the prostate gland
Membranous urethra – segment traveling through the urogenital diaphragm
Penile (spongy) urethra – from diaphragm to urethral orifice

Question 11

What is the micturition reflex? Mechanism?

Answer 11

Stretch receptors in bladder wall senses stretch, 250-400mL volume, signal to PSNS via spinal cord
Cerebral Cortex pathways switch from storage to emptying, allow voluntary control
Micturition is bladder emptying urine out, detrusor muscle contracts, internal urethral sphincter relaxes, external sphincter is voluntarily relaxed
parasympathetic innervation

Question 12

What are hydroureter and hydronephrosis?

Answer 12

hydroureter: dilation of ureter by obstruction
hydronephrosis: distension of renal pelvis, renal calyces by backup of outflow, increases pressure within kidney, damages kidney tissue.

Question 13

What is the most common pathogen in UTI?

Answer 13

E. coli

Question 14

What are the different type of incontinence?

Answer 14

stress incontinence: leakage with increased abdominal pressure (coughing, sneezing)
poor pelvic support and/or weak internal urethral sphincter
urge incontinence (over-active bladder): overactive detrusor muscle
unknown, possibly due to cystitis (inflammation of bladder wall), urothelium dysfunction, nerve damage
overflow incontinence: failure of detrusor muscle
overdistension, urinary retention, obstruction of outflow, damage to pelvic nerves
neurogenic bladder: bladder afferent sensation disrupted – lack of urine release, causes overdistension
functional incontinence: inability to hold urine due to prolonged immobility, CNS problems – stroke, psychiatric disorders, dementia

Question 15

What are the major functions of the kidney?

Answer 15

Maintenance of Blood composition: maintain necessary molecules, eliminate excess
water
ions
acid/base
nutrients: glucose
eliminate metabolic waste, other toxins
Vitamin D activation: hormone involved in Ca2+, PO43- absorption in small intestine
Hormone production
EPO – red blood cell production
Renin – (RAAS Pathway) water/salt conservation

Question 16

What are the structures of the nephron?

Answer 16

Glomerulus
Bowman’s Capsule
Proximal Convoluted Tubule
Loop Of Henle
Descending limb
Ascending limb
Distal Convoluted Tubule
Collecting Duct (Urine OUT)

Question 17

What are the structures of the renal corpuscle?

Answer 17

fed by Afferent arteriole
Glomerulus – knot of fenestrated capillaries, covered in podocytes that form filtration slits
GLOMERULAR FILTRATION: Fluid and small molecules enter renal tubules, blood cells, proteins stay in the blood
drained by Efferent arteriole

Question 18

What is the histology and function of Bowman’s capsule?

Answer 18

Parietal layer – forms outer wall of capsule, simple squamous
Visceral layer – podocytes that cover the glomerulus leaving narrow filtration slits between them
RECEIVE FILTRATE: fluid, small molecules enter before continuing through renal tubules

Question 19

What is the function and histology of the PCT?

Answer 19

Lined with simple cuboidal with microvilli
REABSORPTION: essential small molecules in the filtrate returned to the blood
nutrients
water
ions

Question 20

What is the function and histology of the loop of henle?

Answer 20

Thick segments lined with simple cuboidal
Thin segments lined with simple squamous
CREATES CONCENTRATION GRADIENT: sodium ions moved out of filtrate into the renal medulla, countercurrent blood flow allows gradient to be maintained

Question 21

What is the function and histology of the DCT?

Answer 21

Lined with simple cuboidal, lacks microvilli
CONCENTRATE URINE: water and sodium channels can be opened to remove water and sodium from filtrate (returns water to blood), concentrate urine filtrate

Question 22

What is the function of the collecting duct?

Answer 22

– passes down through the medullary pyramids and receives filtrate from DCT of numerous nephrons
Empties urine into the minor calyces
CONCENTRATE URINE: water and sodium channels can be opened to remove water and sodium from filtrate (returns water to blood), concentrate urine filtrate

Question 23

What cells are present in the juxtaglomerular apparatus? Fxn?

Answer 23

JG cells- part of afferent arteriole, directly contact blood coming in, monitor BP
Macula dense- in DCT- monitor solute composition/how well filtered
JGA- sends hormones to monitor/maintain BP, osmolality

Question 24

What are the 2 types of nephrons?

Answer 24

Cortical nephron – majority of the nephron is within the cortex with a short loop of Henle
Juxtamedullary nephron – glomeruli is deep in the cortex and have a long loop of Henle that extends deep into the medulla

Question 25

What is the blood supply of the kidney?

Answer 25

Renal artery to
Segmental artery, to
Interlobar artery, to
arctuate artery, to
Cortical radiate arteries, to
Afferent arterioles,
to efferent arteriole/ NEPHRON, to
venules, to
interlobar (corticate) veins, to
actuate veins, to
interlobar veins, to
renal vein to IVC